This invention is in the field of percussion-type musical instruments and relates to improvements in musical bars with means to control their ringing decays or sustain period, and to obtain a nearly uniform ringing decay of sounds emanated from such bars in a multi-octave instrument.
It is often desirable in musical bars to control the decay periods of the tone elements. Non-percussion musical instruments, such as violins, woodwinds, horn, etc., have controlled decay, that is, a sustained sound. In case of a violin, for example, the decay period is limited by the length of the bow and the speed with which the bow is drawn across the string. In the case of wind instrument, on the other hand, the decay period is controlled by the supply of air in the lungs of the instrument players. The pipe organ has an almost unlimited air supply and therefore an almost unlimited sound sustaining possibility.
Percussion instruments, by contrast, have inherently variable decay periods, which range from about 30 seconds for the lowest note and to 1/2 second for the highest note in a piano. A xylophone has approximately one second to 1/50 second variable decay period from the low to the high end. Similarly, a marimba bar has a variable decay period of two seconds to 1/50 second from the tenor C in the bass clef to C7, a range of four octaves. Traditionally music played on a marimba in the lower octave has a longer sustained sound because of the slower decay period than that of the upper octaves, where a smooth sustained sound is difficult or nearly impossible to maintain due to the rapid decay of tone elements in that range. For that reason the music played in that range is usually of a more rapid tempo. The solution in the past has been to accept this difference. If the decay periods of the tone elements in the low and high octaves could be made approximately the same, the musical repertoire of marimbas would be greatly enhanced.
It is well known in the musical arts that the vibraphone using tempered aluminum tone bars has the most consistent decay period of all percussion instruments, the decay period being 30 seconds in the low end to about 6 seconds in the high end for a 3 octave instrument. This sustaining tone characteristic, however, is too long to use in rapid note sequences. A damper operated by a foot pedal may be used in such a case to limit the note sequences to the speed of the damper pedal. The vibraphone is used for rapid musical passages, by means of leaving the foot damper closed, thus preventing the full vibration responses of the bars. The tonal timbres in the "damper on" and "damper off" positions, however, are different.
The decay period of the marimba is short enough to permit the play of rapid passages and slow enough for sustained tones in the lower octaves. But this period is too short for effective sustained tones in the upper octaves.